Update custom args

README.md

@@ -24,38 +24,37 @@ And then in your mailers you would do the same `sender.Send(m)` as this sender m
 
 #### Add Custom Args
 
-If you want to send a mail with `custom args`, you need to add it into `mail.Message.Data` as `map[string]interface{}` this will be into `mail.Message.Personalizations` field :
+To add custom args, you must add values using `CustomArgs` type and add it into Message.Data ussing `CustomArgsKey` key
+
+```go
+CustomArgsKey = "sendgrid_custom_args_key"
+...
+type CustomArgs map[string]string
+```
+
+#### How to implement custom args 
 
 ```go
 import (
-    ... 
+	...
     ssender "github.com/paganotoni/sendgrid-sender"
-    bmail "github.com/gobuffalo/buffalo/mail"
 )
 
-var sender mail.Sender
-
-func init() {
-    APIKey := envy.Get("SENDGRID_API_KEY", "")
+func main() {
+	APIKey := envy.Get("SENDGRID_API_KEY", "")
     sender = ssender.NewSendgridSender(APIKey)
-    ...
-    message := bmail.NewMessage()
-    ...
-    customArgs := map[string]interface{}{
+
+	m := mail.NewMessage()
+	...
+    m.Data[ssender.CustomArgsKey] = ssender.CustomArgs{
         "custom_arg_0": "custom_value_0",
-        "custom_arg_1": 100,
-        "custom_arg_2": []string{"val_0", "val_1", "val_2"},
-        "custom_arg_3": map[string]string{
-            "firstName": "John",
-            "lastName":  "Smith",
-            "age":       "24",
-            },
+        "custom_arg_1": "custom_value_1",
         ...
     }
 
-    message.Data = customArgs
-    ...
-
+    if err := sender.Send(m); err != nil{
+        ...
+    }
 }
 ```
 

sendgrid_sender.go

@@ -14,6 +14,14 @@ import (
 	"github.com/stanislas-m/mocksmtp"
 )
 
+const (
+	// CustomArgsKey is used as default key to search the custom args into Message.Data
+	CustomArgsKey = "sendgrid_custom_args_key"
+)
+
+// CustomArgs is the type that must have Message.Data[CustomArgsKey]
+type CustomArgs map[string]string
+
 //SendgridSender implements the Sender interface to be used
 //within buffalo mailer generated package.
 type SendgridSender struct {
@@ -73,8 +81,10 @@ func buildMail(m mail.Message) (*smail.SGMailV3, error) {
 		p.AddTos(smail.NewEmail(to.Name, to.Address))
 	}
 
-	for k, v := range m.Data {
-		p.SetCustomArg(k, fmt.Sprintf("%v", v))
+	if customArgs, ok := m.Data[CustomArgsKey].(CustomArgs); ok {
+		for k, v := range customArgs {
+			p.SetCustomArg(k, v)
+		}
 	}
 
 	html := smail.NewContent("text/html", m.Bodies[0].Content)

sendgrid_sender_test.go

@@ -158,14 +158,10 @@ func Test_build_Mail_Custom_Args(t *testing.T) {
 		},
 	}
 	m.Data = map[string]interface{}{
-		"custom_key_0": "custom_value_0",
-		"custom_key_1": "custom_value_1",
-		"custom_key_2": []string{"val_2", "val_3", "val_4"},
-		"custom_key_3": 25,
-		"custom_key_4": map[string]string{
-			"firstName": "John",
-			"lastName":  "Smith",
-			"age":       "24",
+		CustomArgsKey: CustomArgs{
+			"custom_key_0": "custom_value_0",
+			"custom_key_1": "custom_value_1",
+			"custom_key_2": "[val_2 val_3 val_4]",
 		},
 	}
 	m.Attachments = []mail.Attachment{
@@ -186,14 +182,10 @@ func Test_build_Mail_Custom_Args(t *testing.T) {
 	mm, err := buildMail(m)
 
 	a.NoError(err)
-	a.Equal(5, len(mm.Personalizations[0].CustomArgs))
+	a.Equal(3, len(mm.Personalizations[0].CustomArgs))
 	a.Equal("custom_value_0", mm.Personalizations[0].CustomArgs["custom_key_0"])
 	a.Equal("custom_value_1", mm.Personalizations[0].CustomArgs["custom_key_1"])
 	a.Equal("[val_2 val_3 val_4]", mm.Personalizations[0].CustomArgs["custom_key_2"])
-	a.Equal("25", mm.Personalizations[0].CustomArgs["custom_key_3"])
-	a.Contains(mm.Personalizations[0].CustomArgs["custom_key_4"], "firstName:John")
-	a.Contains(mm.Personalizations[0].CustomArgs["custom_key_4"], "lastName:Smith")
-	a.Contains(mm.Personalizations[0].CustomArgs["custom_key_4"], "age:24")
 
 	m.Data = map[string]interface{}{}
 	mm, err = buildMail(m)
@@ -202,4 +194,5 @@ func Test_build_Mail_Custom_Args(t *testing.T) {
 	a.Equal(0, len(mm.Personalizations[0].CustomArgs))
 	a.Equal("", mm.Personalizations[0].CustomArgs["custom_key_0"])
 	a.Equal("", mm.Personalizations[0].CustomArgs["custom_key_1"])
+	a.Equal("", mm.Personalizations[0].CustomArgs["custom_key_2"])
 }